Rolling mill stand

ABSTRACT

For inserting and removing packers into and from a rolling mill stand having roll adjusting hydraulic piston and cylinder assemblies in the top of each stand housing, a packer-carrying sledge runs on tracks extending into the stand below the lowermost rolls of the stand. The sledge is located in the stand during rolling and can carry packers which are located operatively between the chocks of the lowermost roll and the housings.

This invention relates to a rolling mill stand and, particularly, to arolling mill stand for rolling material such as metal, the stand havinga pair of spaced housings, each having therein a window to receive thechocks of the rolls, or some of those chocks. The invention is primarilyconcerned with a 4-high mill stand having a pair of work rolls and apair of back-up rolls, but it is applicable to other stands, andparticularly to a 2-high stand.

The invention particularly relates to a rolling mill stand in which eachhousing has roll gap adjustment means to act between the top of thehousing and the uppermost roll. The roll gap adjustment means arepreferably piston and cylinder assemblies, but they may be mechanicalscrewdowns.

In a rolling mill stand of the type having hydraulic piston and cylinderassemblies in the housings for adjusting the roll gap, it is usual tohave those assemblies in the bottoms of the housing windows, actingupwardly on the roll stack. That arrangement has certain practicaldifficulties, which are removed by the location of the assemblies in thetops of the housings, acting between the housings and the uppermost rollof the roll stack.

When the piston and cylinder assemblies are located in the bottoms ofthe windows, there is little difficulty in placing packers at the topsof the windows, in order to maintain a substantially constant pass-lineregardless of roll wear. However, when the assemblies are located in thetops of the housings, packers cannot be easily replaced because theweight of the stack acts on them and because the bottoms of the windowsare less accessible than the tops.

In order to facilitate packer interchange, in a rolling mill standcomprising a pair of spaced housings having windows therein to receivebearing chocks of rolling mill rolls, and roll gap adjustment meanscarried by each housing to act between the top of the housing and theuppermost roll, the present invention provides sledge means movablebetween an inoperative position outside the housings and an operativeposition at the bottom of the windows, the sledge means being in theoperative position during rolling; means on the sledge means forcarrying packers to be disposed operatively between the bottom of eachwindow and the lowermost roll; and means for lifting the rollssufficiently to permit movement of the sledge means between theoperative and inoperative position. When it is desired to changepackers, the sledge means can be removed to the position outside thehousings, the packers interchanged, and the sledge means returned to thestand.

The sledge means may comprise a separate sledge for each housing, but inthat case it is advantageous to have them connected so as to movetogether between the operative and inoperative positions; both sledgescan then be withdrawn to the operator's side of the mill and it becomesunnecessary for the operator to reach the relatively inaccessible driveside in order to change the packer at that side. It is however preferredto have a single sledge on which packers for both housings are carriedand which can be withdrawn to the operator's side; the packers on thedrive side of the mill stand can then be interchanged again at theoperator's side of the stand, at the same time as the packers at theoperator's side, and packer interchange is facilitated and expedited.

Preferably, the sledge is in the form of a carriage and the packercarrying means are trays for the housings adapted to receive packers.The trays are preferably removable from the carriage, and may be mountedon upwardly acting resilient means.

The sledge may be employed to remove the rolls from the housings.Further, the sledge facilitates removal of the work rolls of a 4-highmill stand, in that the withdrawal of the removable trays enables thelower back-up roll to be lowered to allow the work rolls to be supportedon roll-change tracks.

The invention includes methods of operating the rolling mill stand forreplacing the packers, replacing the work rolls, or replacing all therolls, with or without the piston and cylinder assemblies, when providedfor roll gap adjustment.

The invention will be more readily understood by way of example from thefollowing description of a rolling mill stand in accordance therewith,reference being made to the accompanying drawings, in which:

FIG. 1 is a vertical section of the mill stand, taken on the line I--Iof FIG. 2,

FIG. 2 is a section on line II--II of FIG. 1, and

FIG. 3 is a perspective view of part of the sledge means.

The metal rolling mill stand shown in the drawings comprises a pair ofspaced housings 11, 12, each having a vertical window 13. The roll stackof the stand as shown comprises upper and lower back-up rolls, 14, 15and upper and lower work rolls 16, 17. The necks of each of the back-uprolls 14, 15 are journalled in chocks 20, which are slidably received inthe housing windows 13. Similarly, the work rolls 16, 17 have chocks 21which are guided by blocks 22 secured to the housings.

A piston and cylinder assembly 23 is located in the top of each window13, so as to act between the tops of the housings and the chocks 20 ofthe upper back-up roll 14. Each piston and cylinder assembly 23 is heldin place by keepers 24 detachably secured to the housings.

At the bottom of the housings 11, 12, there is sledge means in the formof a carriage 25, which consists of a pair of vertical side plates 26,which are equally spaced from the centre line of the mill stand andwhich are tied together, and two pairs of wheels 27, 28. The wheels 27on one side of the carriage means are flanged and run on a rail 30,while the other pair of wheels 28 are unflanged and run on a parallelrail 31; rails 30, 31 are mounted on the housings and extend betweenthem. A rack 32 is formed on the inner face of the plate 26 adjacent thewheels 27, and meshes with a pinion 33 of a hydraulic motor 34. Byactuation of the motor 34, the carriage can be driven parallel to theaxes of the rolls between an operative position within the housings andbetween the bottoms of the windows and the chocks 20 of the lowerback-up roll 15, and an inoperative position outside the housings.

The carriage 25 further carries, for each housing 11, 12, a pair ofresilient means 35, 36, in the form of upwardly-biased spring plungers.The resilient means 35, 36 for each housing supports the wings of a tray37 for that housing, the tray extending between the resilient means andlocated between the plates 26. Each tray is arranged to receive one ormore packers, an example of which is indicated at 38.

Each chock 20 of the lower back-up roll 15 is formed with a downwardlydirected tongue 40 which can be received within the tray 37, as shown inFIG. 2, and has also oppositely directed wings 41, extending beyond therails 30, 31. Beneath the extremities of the wings 41 are located a pairof piston and cylinder assemblies 41, which on actuation can engage thewings 41 and lift the stack of rolls off the packer 38 and tray 37.

During rolling, the sledge is in the operative position as shown in thedrawings. When the piston and cylinder assemblies 23 are operated, thestack of rolls are 7 forced downwardly, overcoming the bias of thesprings of the resilient means 35, 36 and causing the trays 37 to engageagainst the upper surfaces of load cells 43 seated on the bottom of thehousing window. The rolling load thus passes, in each housing, directlyfrom the chock 20 of the lower backup roll 15, and through the packer38, the tray 37 and the load cell 43, to the bottom of the housing;little, if any, of the rolling load is transmitted through the carriage25 and the rails 30, 31 to the housing.

If it is desired to change packers (38), to compensate for roll wear,the cylinders of the assemblies 23 are exhausted and the assemblies 42are actuated to lift the roll stack, so that the tongues 48 are liftedclear of the packers 38. The resilient means 35, 36 then operate toraise the trays 37 off the load cells 43. Hydraulic motor 34 is actuatedto traverse the carriage out of the stand, that movement of the carriagebeing effected without damage to the surfaces of the load cells 43, asthe trays 37 are no longer in contact with them. The packers 38 can thenbe replaced as required, outside the stand, and then returned to theiroperative positions, by reversing the sequence of operation justdescribed.

For work roll change, the cylinders of assemblies 23 are exhausted andthe assemblies 42 are actuated, as before. The carriage 25 is traversedout of the stand and the trays 37 removed and the carriage returned tothe stand. The upper roll 14 is retained in its elevated position bymeans of hydraulic rams 49 in the blocks 22, and then the assemblies 42are exhausted so that the wings 41 become seated on, and supported by,the side plates 26. During the downward movement of the work rolls andlower back-up roll, wings 45 extending outwardly from the chocks 21 ofthe lower work roll 17 engage lugs 46 on rails 47, which are carried bythe housings, which extend between those housings, and which are movablelengthwise. When the work rolls are supported by the lugs 46 and thelower back-up roll is supported by the plates 26, the lower work roll 17is out of contact with the lower back-up roll 15, and the work rolls canbe removed from the mill by moving the rails 47, with the work rollscarried on the lugs 46. The new work rolls are replaced in a similarfashion, fresh packers, appropriate to the diameters of the new workrolls, being located on the trays 37 before the latter are returned tothe stand.

To remove all the rolls from the stand, the stack is raised by theassemblies 42, the carriage 25 traversed out of the stand, the trays 37removed, and the carriage returned to the stand as previously described.The rails 47 are removed, and the assemblies 42 exhausted so that thestack is lowered until it is supported by the side plates 26 of thecarriage. The hydraulic motor 34 is finally actuated to drive thecarriage with the superposed stack, out of the stand. The new stack isinserted in the stand by the same procedure in reverse order. Before thetrays 37 are returned to the housings, packers appropriate to the newrolls are inserted.

If desired, the hydraulic piston and cylinder assemblies 23 can beremoved from the housings, with the roll stack. For that purpose, thelatches 24 are first removed, so that the assemblies 23 are seated onthe chocks 20 of the upper back-up roll 14, and can be removed togetherwith those chocks.

What I claim as my invention and desire to secure by Letters Patent is:
 1. In a rolling mill stand having(a) first and second spaced housings each having therein a window; (b) a plurality of rolls; (c) bearing chocks for each said roll, (d) the chocks of at least some of said rolls being slidingly received in said windows; and (e) roll gap adjustment means carried by each said housing to act between the top of said housing and the uppermost of said rolls;equipment for inserting and removing packers into and from said stand, said equipment comprising (f) a carriage movable parallel to the axes of said rolls between an inoperative position outside said housings and an operative position at the bottom of each said window, (g) said carriage being in said operative position during rolling; (h) a pair of trays for carrying packers to be disposed operatively between the bottom of each said window and the lowermost of said rolls; (i) upwardly acting resilient means on said carriage for supporting each said tray, which resilient means are located in each window when said carriage is in operative position and lift each said tray away from the bottom of the associated window unless each said tray is forced down by said rolls into contact with the bottom of the associated window; and (j) means for lifting said rolls sufficiently to permit movement of said carriage between said operative and inoperative positions with said trays lifted by said resilient means.
 2. Packer inserting and removing equipment as claimed in claim 1, further comprisinga load cell in the bottom of at least one of said windows, one of said trays being disposed over said load cell when said carriage is in said operative position, said resilient means ensuring that, during rolling, a chock of said lowermost roll is supported by said load cell through said tray, and, during movement of said carriage, said tray is lifted out of contact with said load cell.
 3. Packer inserting and removing equipment as claimed in claim 1, in said which trays are removable from said carriage, and said carriage has upwardly extending support members to engage the chocks of said lowermost roll when said trays have been removed.
 4. In a rolling mill stand having(a) first and second spaced housings each having therein a window; (b) a plurality of rolls; (c) bearing chocks for each said roll; (d) the chocks of at least some of said rolls being slidingly received in said windows; and (e) roll gap adjustment means carried by each said housing to act between the top of said housing and the uppermost of said rolls;equipment for inserting and removing packers into and from said stand, said equipment comprising (f) a carriage movable parallel to the axes of said rolls between an inoperative position outside said housings and an operative position at the bottom of each said window, (g) said carriage being in said operative position during rolling; (h) packer carrying means on said carriage including a pair of removable trays for carrying packers to be disposed operatively between the bottom of each said window and the lowermost of said rolls when said carriage is in operative position; (i) upwardly extending support members on said carriage to engage the chocks of said lowermost roll when said trays are removed; and (j) means for lifting said rolls sufficiently to permit movement of said carriage between said operative and inoperative positions. 